Only limited clinical data are available to establish the risk factors for adverse events and their frequency among children who have received oral beta-blockers in a critical care unit setting. The authors aimed to analyze the frequency of adverse events experienced by children treated with oral beta-blockers in a cardiovascular intensive care unit (CVICU) and sought out independent risk factors for these adverse events in a tertiary care hospital. The primary end point in this retrospective descriptive study was the incidence of adverse events associated with enteral beta-blocker administration, and the secondary end point was the incidence of readmission to the CVICU after transfer of patients to an acute care floor. At least one clinical adverse event occurred for 38% of the patients. Specifically, the profile of the clinical adverse events included bradycardia in 27 patients (11%), hypoglycemia in 46 patients (19%), and the initiation or escalation of inotropes in 36 patients (15%) after oral beta-blocker administration. Additionally, 41 patients (17%) were readmitted to the CVICU after transfer during the same hospital admission. The patients receiving propranolol were predisposed to have at least one adverse event (p = 0.045). No other patient-specific characteristics significantly predisposed patients to adverse events. The patients admitted after a cardiac procedure had fewer readmissions to the intensive care unit (ICU) during the same hospital admission (p = 0.002). The results demonstrated that adverse events are relatively common among patients receiving oral beta-blockers in a CVICU population. Because these children have less physiologic reserve, more must be done to ensure that the correct beta-blocker is prescribed to avoid clinically significant adverse events that may hamper the recovery of these patients and lead to increased ICU time.